Apparatus for dressing involute surfaces on grinding wheels



July 22; 1947. w SHQTEY 2,424,507

APPARATUS FOR DRE SSING INVOLUTE SURFACES ON GRINDING WHEELS Filed Feb. 28, 1944 2 $heets-Sheet l INVENTOR Mama 550222.

Y TORNEYSP vW. SHOTEY APPARATUS FOR DRESSING INVOLUTE SURFACES 0N GRINDING WHEELS July 22, 1947.

2 Sheets-Shget 2 Filed Feb. 2 1944 INVENTOR v MLLJ MJ BY.-

Ml v g TTORNEY-S According to the preferred V ;invention, the amplitude is less than 180 degrees within the base circle in order to provide. the.

Patented July 22, 1947 APPARATUS roan sunmor s on G RESSING INVOLUTE RINDING WHEELS V :S liq tey, Dearborn, Mich. Appiicauonr pruaiy za, 1944, Serial No. 524,222

This invention is an vice shown in my United States PatentNo. 1,912,4

10 of June 6, 1933. H In that patentis'shown lense (01. 125-11) improvement ofathe dea device for forming concave involute surfaces ,on grinding wheelsused in finishing involute,

gear teeth. The device includes an arcuate ;member having the radius of the base circleiof -;the involute, a tangent 'bar clamped on the pe-l ;i=ipl1ery of the arcuate member ina manner .to

roll involutely thereon, and a dressing'tool carried ihy the bar such that its point generates an-in-i yolute. The point is positioned to lie in the plane: or" tangency so that it commences to generate its involute directly at the base circle. It hasbeen found in practice that, as a result of this relate tionship, a fillet is formed on the to the base circle of the involute. a

The object of the present inventionis-togover-s come this difficulty and is accomplished generally by starting the involute slightly inward of the base circle. For this purpose the axis 01 v thegtoql; is displaced slightly inward from theplhnenofz tangency, preferably in an angular relatiomto i that plane, A means is provided for adjusting; the angle or the increment added to theinvolute within the base circle. H r 1 Y The tool carrier is mounted to be rotated-,rrom one side of the dressing wheel to the other. 111 the patent this rotation is exactly 180 degrees.

embodiment of the aforementioned increments of the involutej The tdecrement from 180 degrees of amplitude is, variable by means of adjustable stop members in the tool carrier, inasmuch as various designs of gears require varying increments to the-in- "vol-ute. V The invention is fully disclosed by way ofeX- ample in the following description andin;the. accompanying drawings in which: 1. 1:

Figure 1 is a plan view of therdevice. Figure 2 is a vertical section, partly in ele vation. a

Figure 3 is a section on the line ure 2;

Figure 4 is a ure 2'; p Figurefi is an enlarged detail of Figure 2;"1 1.

Figure 6 is a vertical elevation at right angles to Figure 2; 2

Figure 7 is a section on the line 'l- Tof Flg ure6,and 1 Figure 8 is a diagram illustrating the opera p section on the line 4- 41 of" "Fig-l wheel adjacent tion of the apparatus as viewed in the plane of Figure 6. l 7

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

in Figure 1 is shown a base I on which is formed astandard 2 carrying a stud 3. On the stud are mounted a pair of spaced disks 4 which are congruent and of equal circumference.

On the stud 3 and between the disks is pivotally mounted an arm 5. A bushing 6 is fitted between the stud and the arm, and a set of rollerbearings 1 is mounted between the bushing and'arm. A nut 8 on the stud 3 tightens the as- ,semblyagainst a washer 9 on the stud,.thereby fixingthe disks. 4 while permitting the arm to swivel as will presently be described. The disks Ahav'e the circumference of the root circle or" the involute .to be formed, and various sizes of disks are interchangeable on the stud.

Abovethestud 3, the arm has a vertical slot lflsfrom the. upper endof which extends a tapped holenl I,.through the upper end of the arm. A pin l2.is slidably mounted in the slot and carries disks 13 on both ends, which project beyond the surfacesbf thearm Roller. bearings are inserted between each disk and pin I2. A threaded stud: l 5 fistscrewed into the hole I l and is adapted to bear upon the pin [2 when the latter is in an elevated position in the slot 10,

UDQn the. disks .4is mounted a frame-like tansent barJZQ having ajo rn 2 e t n in laterally fromits midpoint. In the initial position of the built), the axis ofthe journal is in the plane of-t neency and pa allel to the central axi of t disks; Such initial position is secured, in setti eqthqappar t s; y a p n 2 passed through a block; 2 3;slidable in a Slot 2' in the upright 2 andenteringan aperture 23' in the tangent bar.

the-, slot 2 by a headed screw 22.

The journal 2-! supports a tool carrier which includes a hub 24 rotatably mounted on the journ al;.andan arm' 25 extending outwardly there- ;IThe-block is secured in the desired p0sition in from parallel to the axis of thehub. The outer end of the arm has a -V-s1ot 26 whose bottom is parallel to the disks land which is designed to receive-a pointed dressing tool-2 1. 1 A cap 28 is fastened onthe grooved end :Of the arm 25 by screws 29; and carries a set screw 30 for fixing the tool in the groove. 1'I'he"carrier is heldrotatalbly on the journal 2| by astud- 3| passed through the outer .end ofqthe' hub 24 and threaded intoa hole. inqthe journal; A shoulder3l' of thewstudclamps against-the journal 2!, and a spring washer 30 secures the stud frictionally against the hub 24 by a key fit 32 on the stud.

The hub 24 is formed with a slot 33 transverse of the hub aXis and having an extent of somewhat more than 180. A stop pin 34 positioned in the slot is fastened radially to the journal 2|. Normally the rotation of the hub on the journal would be limited by the engagement of the pin 34 by the bottom 33' of the slot at either side of the center of the bottom. The arcuate extent of the slot is preferably so related to the diameter of the pin 34 that the hub may be turned side to the other of the wheel 40.- This amplitude is, however, of bumper screws 35 mounted in the hub 24 parallel to each other at opposite sidesof=the aforementioned center of the bottom 33 and,

adapted to pass through said bottom into the slot. Thus, the amplitude of the hub 24Ltis-adjustably reduced below 180, and this reduction may vary between wide limits. of the screws 35 is secured by set screws: ilii in the hub 24.

The wheel 40 to be dressed is mounted on a. rotating spindle 4|, andthe dressing apparatus,

is positioned so that the point of the tool 21 lies initially at one side of the wheel anclgat its periphery. The screw i is tightened on the pin I2 so that the disks l3 clamp the tangent bar 20 on the disks 4. The arm 5 may then be oscillated manually on the bearings grasping the upper end thereof with thewresult that the clamped tangent bar 20 rolls on the disks 4 without slipping relatively thereto. quently any point on the tangent bar describes an involute path, and this is also true of the point of the tool 21.

With the bumpers 35 adjusted tosextend slightly into the slot 33, the point-31 of the tool 21 lies slightly below the base circle of. the involute or within the circumference of the disks 4., it being noted in this connection that thercenter of rotation of the tool carrier is in the axis of tangency, that is, in line with the-points ofthe tangency on the disks 4, and that the entire tool 21 is at one side of the center of rotation.

The result of this arrangement, illustrated diagrammatically in Figure 8, is that thetool point commences to enerate an involute aslight distance inward of the base circle. Inother words, the bar 20 is adjusted so that it is tangent to the base circle where the latter is intersected by the involute to be formed. The-point of thetool 21' is then positioned so that it lies entirely inward of the circle and of the lineof tangency, thatis, the point is not bisected by the line of tangency. This condition is illustrated in an-exaggerated degree in Figure 8. A suitable device, well known in the art, is provided for feeding the wheel downwardly in small-increments across'thetool point in order to maintain the wheel in contact with tool during the dressing operation;

To the extent by which the wheelisfed-dnwardly beyond the initial position of the tool point, a flat annular surface 42 is formed on the side of the wheel at the periphery. This condition results from the fact the initial position of the tool point is a limit position'beyond which the point cannot move inward of the base circle, and the wheel moving across this-position of the point in the feeding direction can therefore be formed only with the fiat surface 42.

The other side of the wheel is dressed in like manner after swinging the carrier 24-'3l withthe tool until the remaining bumper '35 stops 180 from one to be dressed. reducedby aipair" The adjustment.

1, for example by Consethe actual point of the tool has some area, it is notpracticallypossible to set the apparatus so that. the; tool; will commence cutting the wheel exactly at its periphery. Consequently, a fillet is formed wherethe involute begins or the peripheraledgemay be chipped. The apparatus herein described overcomes this difficulty by starting the involute at a point inward of the base circle. A perfect cut is made on the first operation, and a second cut for removing a fillet is not necessary.

Although a specific embodiment of the invention-hasbeen shown and been described, it will. be undersood; that various alterations may be made without departure from the spirit of the invention as indicated by the appended claims.

Having. fully described my invention, what I claim and desire to secure by Letters Patent is: 1. An apparatus for dressing grinding wheels, comprising a base, an arcuate member carried thereby, a tangent bar laid on the periphery of said member, an arm pivotally mounted at the center of said member, means on said arm for clamping said bar on said periphery, whereby said bar may be rolled involutely on said periphery, a journal extending laterally from said bar and having its axis in the axis of tangency, a tool carrier rotatably mounted on said journal, said carrier'having a seat positioned to hold a dressing 'tool with its axis alongside said arcuate member,

tation of said carrier on said journal.

2. An apparatus for'dressing grinding wheels, comprising 'a base, an arcuate member carried thereby, a tangent bar laid on the periphery of said'member, an arm pivotally mounted at the center of said member, means on said arm for clamping said bar on said periphery, whereby said bar may be rolled involutely on said periphery, a journal extending laterally from said bar and having its axis in the axis of tangency, a tool carrier 'rotatablymounted on said journal, said carrier having aseat positioned to hold a dressing tool with its axisalongside said arcuate member, whereby the axis of said seat travels involutely with saidba-r, a stop member extending from the circumference of said journal, said carrier having aslot of substantially transverse of the axis of said journal and receiving said stop member, andtwobumpers adjustably mounted in said carrier and extending from said carrier into said slot at oppositesides of said stop member to engage the latter and limit the rotation of said carrier on said journal.

3. An apparatus for dressing grinding wheels, comprising'a base, an-arcuate member carried thereby, a tangent bar laid on the periphery of said 'member, an arm pivotally mounted at the center of said member, means on said arm for clamping said bar on said periphery, whereby said bar may be rolled involutely on said periphery, a journal extending laterally from said bar and having its aXis in the axis of tangency, a tool carrier rotatably mounted on said bar on an axis perpendicular to said arcuate member, said carrier having a seat positioned to hold a dressing tool with its axis alongside said arcuate member, whereby the axis of said seat travels involutely with said bar, a stop member extending from the circumference of said journal, said carrier having a slot of substantially 180 transverse of the axis of said journal and receiving said stop member, and two bumpers extending from said carrier into said slot at opposite sides of said stop member to engage the latter and limit the rotation of said carrier on said journal.

4. An apparatus for dressing grinding wheels, comprising a base, an arcuate member carried thereby, a tangent bar laid on the periphery of said member, an arm pivotally mounted at the center of said member, means on said arm for a tool carrier rotatably clamping said bar on said periphery, whereby said bar may be rolled involutely on said periphery, mounted on said bar on an axis perpendicular to said arcuate member to turn through a maximum arc of 180, stop means for reducing the extent of rotation at either end of said are, a pointed tool mounted in said carrier and having its point displaced from the plane of tangency slightly toward the center of said arcuate member, whereby the involute path of said point intersects the right cylindrical surface projected from the periphery of said arcuate member.

WILLIAM SHOTEY.

REFERENCES CITED UNITED STATES PATENTS Name Date Shotey June 6, 1933 Number 

